The magnetic compresseion has been applied for a Ultra-low-q (ULQ) plasma with a safety factor q (a) of less than unity, where the toroidal magetic field B_t was increased from 0.1 T to 0.3 T.During the magnetic compression phase, the increases of the loop voltage and magnetic fluctuations have been observed, indicating the enhancement of the resistance anomaly. This might be accounted for a poloidal electric field induced by the rapid increase of the toroidal magnetic field, the direction of which is opposite to the incident dynamo electric field. H_<alpha> signals have drastically suppressed during the magnetic compression, accompanied by the shrinkage of the plasma column with a few centimenter.Just after the magnetic compression the plasma current begins to increase, and the loop voltage and magentic fluctuations are kept at low levels during this phase. Compared with the scaling of resistance anomaly for ULQ plasmas, the plasma resistance of this phase is quite low, and more stable and quiescent ULQ plasmas have been realized by applying the magnetic compression for ULQ plasmas. This stable ULQ configuration terminates when the rational surface appears at the plasma surface, accompanied by the increase of magnetic fluctuations and the anomalous ion heating. It is found that the magnetic compression is very powerful to introduce an externally-induced poloidal electric field and to understand the role of the dynamo electric field in ULQ plasmas.磁気圧縮直後からプラズマ電流が増加しはじめ、しかも周回電圧も低い値に保持されている。この電流増加フェーズでは、磁場揺動やHαシグナルも低い値で保持されており、イオン異常加熱も観測されていない。通常のVLQプラズマ異常抵抗に関するスケーリング則と比較しても、この電流増加フェーズのプラズマ抵抗値は低い値に保持されている。これらの結果から、磁気圧縮によりMHD的により安定なULQプラズマ配位が形成されたと言える